Make gas use statistics be coherent and more complete

The gas use logic in the dive statistics page is confused.

The SAC case had a special case for "unknown", but only for
the first gas. Other gases had the normal empty case.

Also, the logic was really odd - if you had gases that weren't used (or
pressures not known) intermixed with gases you *did* have pressure for,
the statistics got really confused.

The list of gases showed all gases that we know about during the dive,
but then the gas use and SAC-rate lists wouldn't necessarily match,
because the loops that computed those stopped after the first gas that
didn't have any pressure change.

To make things worse, the first cylinder was special-cased again, so it
all lined up for the single-cylinder case.

This makes all the cylinders act the same way, leaving unknown gas use
(and thus SAC) just empty for that gas.

It also fixes the SAC calculation case where we don't have real samples,
and the profile is a fake profile - possibly with gas changes in between
the fake points. We now make the SAC calculations match what we show -
which is admittedly not at all necessarily what the dive was, but at
least we're consistent.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Remove left overs from time zone designation in Windows/Spanish

We remove the time zone designation when showing times (as all our times
have no timezone). But the Spanish localization on Windows shows the time
zone in parenthesis - and the existing code then left those parenthesis
behind which looked very strange.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Attempt to hack around the problems with Swedish date localization

When trying to shorten the long date format into a "medium" length date
format we are messing up Swedish dates. This should fix the issue. Not a
great solution but should be good enough for 4.2

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>